Estimates of the global wind power resource over land range from 56 to 400 TW. Most estimates have implicitly assumed that extraction of wind energy does not alter large-scale winds enough to significantly limit wind power production. Estimates that ignore the effect of wind turbine drag on local winds have assumed that wind power production of 2–4 W/m2 can be sustained over large areas. New results from a mesoscale model suggest that wind power production is limited to about 1 W/m2 at wind farm scales larger than about 100 km2.

David Mackay, the chief scientist at DECC, has this to say about the UK's onshore wind resource:

...if we covered the windiest 10% of the country with windmills (delivering 2 W/m2), we would be able to generate 20 kWh/d per person, which is half of the power used by driving an average fossil-fuel car 50 km per day.

If the true figure is 1 W/m2, we could cover half the country with windmills and still not get enough energy for the average daily commute.

In this lecture, Professor Watson will explore the potential future role of natural gas in the UK energy mix, and will discuss some of the reasons why this is so controversial.

Jim Watson is Professor of Energy Policy at SPRU, University of Sussex. ... He frequently advises UK government departments and other organisations. He ... has been a Specialist Adviser with House of Commons Committees on... Energy and Climate Change (2010-11).

As I said in a posting on a slightly different subject on the "Watts Up With That?" blog, the power output from wind turbines could be increased if in periods when there was no wind everyone feeling cold due to power cuts could go out and blow hard on the blades!

That would kill two birds with one stone. It would solve the problem of wind power being unreliable and it would help to keep people fit at the same time!

Why did it take the scientific and engineering communities decades to discover that there is something called "wind shadow?" I could have explained "wind shadow" when I was ten years old. But I had the huge advantage of growing up on a working farm.

"A sunny day delivers up to 1000W/m2, which can be quite efficiently extracted with thermal solar panels."

I do not understand how someone who lives in England could believe that solar panels have something to contribute in the area of energy conservation. At DisneyWorld, my solar panels managed to heat my bath water for eight months of the year. Yes, they were inspected and working properly.

This may be a sign some are catching on to the problems with wind power. (Or at least here "across the pond" some are.) Small coastal cities in New England are wondering what the heck to do with their malfunctioning wind turbines, and in some cases just take the darn things down.

The effect of wind shadowing is taken into account somwehat in the design and layout of turbines in the UK. There are two main effects of putting turbines too close together. Firsty, downwind turbines see a lower wind speed and produce less electricity. Secondly, downwind turbines see the turbulence and vortices produced by upwind turbines. This also reduces the electrical output, but also leads to increased loads and extra wear and tear on the turbines. However, the subsidies are so huge that it pays developers to cram in as many turbines as they can regardless. Sometimes a developer will get planning permission for a wind farm and then sell on the planning permission to some other unsuspecting greedy developer.

Here in mid-western France, in an area of high sunshine (2000 hours/year); I can heat my water for about eight months of the year with a 4m² panel. The problem is that this is during the summer months when I use less hot water than in the winter.

Many farmers in this area are rebuilding their barns and putting PV panels on the whole of the roof. They have a huge subsidy for this and for the electricity produced. Utter madness.

Seventeen years of continuous surveys covering countries around the world show that people not only do not care about climate change today - understandably prioritising economic misery - they also did not care about climate change even back when times were good.

The new information comes in a study released by the National Opinion Research Center at the University of Chicago - a large, long-standing and respected non-profit. The results are based on surveys which began in 1993, back in the boom times, and “are the first and only surveys that put long-term attitudes toward environmental issues in general and global climate change in particular in an international perspective,” according to NORC's Tom W Smith.

[...]

The NORC spokespersons add that decades of climate alarmism have had basically no effect on people's attitude around the world:

"The latest surveys were completed in 2010. Similar surveys have been conducted since 1993, and little change has been noted on people’s concern for climate change ... widespread public support for current action on the issue will represent a major shift in attitude."

@John de MelleI don't which part of France you're in but here in the Limousin they're building new barns covered in PV.

I still have trouble with:-1. Using a source which only works 50% of the year and best on cloudless days and is unpredictable2. Using a source which is unpredictable and doesn't work at low or high speed.3. Using a source which has a 12.33 hr on off cycle (predictable I suppose)4 Using a source which is unusable during droughts and lowrainfall periods.5 Using a source which puts up the price of food and fuel for the poorest in the world

There is a deflection strategy going on here - it is; good wind = sea, bad wind = land.

When all the time, the strategy and mindset of sensible people and engineers all around the world is wind power went out of 'fashion' before the Victorians booted it back to the antiquity where they reasoned it belonged.

The drag effect, is not simply restricted to land based birdchompers - the drag effect works just the same at sea.

Out of sight out of mind - HMG GREEN Seagull-mincers policy and ££££billions of YES = YOUR MONEY!!! - sent down to Davy Jones's locker.

E=MxVxV. Reducing Velocity has a large effect on Energy. This is a well known relationship to engineers and should not need pointing out by scientists. The fact that it has been only serves to highlight the corrupting effect of subsidies.

I oftne look at "Electricity Generation by Fuel Type" on the bmreports.com website.

Interesting to see Wind is at 2.3% today but was down to 0.1% last week and has been at 0% before now.

Is it just me or is Solar PV not anywhere in sight on here? You don't have to travel far in the UK to see a PV installation on the roof of a house but are they really not making any significant amount of electricity?

Jack Hughes: What you see on bmreports is only the generators that the grid sees. So for wind it is only the big wind farms, mainly in Scotland. The actual installed capacity is much greater than reported. The grid does not see embedded generators such as small wind farms, individual wind turbines, solar panels etc, so it has no idea how much electricity is actually being generated by thousands of these schemes. It just makes the work of the grid, trying to balance supply with demand, that much harder.

"I do not understand how someone who lives in England could believe that solar panels have something to contribute in the area of energy conservation."

I was just reinforcing the idea that the power density claimed for windmills was pretty pathetic, not trying to make a case for solar, although the relatively simple heat absorption panels used for pre-heating water work tolerably well. They were popular in the 70's for a while, after the fuel crisis, and I have some friends whose 35-year old installation is still working.

I can't see many solar PV systems lasting that long, and of course they wouldn't have been installed in the first place without the subsidies.

Strange that the figure for wind is a couple of watts per square metre. That is the same amount as the increase in warming due to delta CO2. Yes, I know they are different things which happen to be measured in the same units, but when I asked for an observation of delta CO2 effects I was told you can't find two watts per sqm, it is 'lost in the noise'. Perhaps that is where the windmill contribution is, lost in the noise.

Just imagine. Walking the footpaths of the UK, you top a ridge and see the natives gathered in a circle beside the local wind farm, frozen harder than rock, dust gathering over them as they become fossils at the alter of green lunacy. You flip in your travel guide and see that your next stop is Stonehenge. As you slowly make your way toward the circle, you wonder if that was how Stonehenge really came about. History repeating and all that.

Interesting to see the article on "large wind farms". As I know of the Laws of Conservation of Energy, I have always wondered why this thinking was not used against wind farms. If you take energy out of the wind, you cannot then get the same amount out next time. I was looking for some wild ideas of how to reconcile the two. But the Laws of physics still work thank goodness. It was a long time ago since I was at school but I do remember some things.

@ JamesP "A sunny day delivers up to 1000W/m2, which can be quite efficiently extracted with thermal solar panels."

At our latitudes, averaging peak insolation over the year results in 10%, so your 1 kW/m2 comes down to 100 W/m2 average. Again here the problem is how to store the peak energy to make use of this average 100 W/m2 insolation (which, through Si band gap efficiency results in an absolute maximum of 14W/m2 electrical energy).

The reason that the average is so much lower than the peak is the fact that, for example during winter with extended high pressure spells, there are long periods, sometimes a week long, when there is almost zero output.

An example: in a medium size house, standing on its own ground, average electric power use is about 1kW continuous. For this about 65 m2 solar panels are required, with optimum sighting. This value is obtained from practice at a large site close to where I live. They have 650 m2 top quality panels yielding 100kW peak with a yearly average of 10kW. One week of electrical energy storage for a house would be 1kW x 24 x 7= 168 kWh, which would mean 168 fairly large lead-acid batteries with associated equipment. These batteries can stand about 500 charge/discharge cycles before they would have to be replaced. This means they would last from 2 - 5 years.

The conclusion is that at our latitudes solar energy is even more useless for general electric power without fossil fuel backup than wind energy. It may be a little bit useful for pre-heating your hot water, but in winter even that is useless, especially when there is a lot of frost.

Due to the low incidence of sunlight in relatively high northern climes, the particular cloudiness of the UK, and the fact that in the UK peak energy demand is in winter at night, solar PV is obviously inefficient and is unlikely ever to provide a worthwhile source of energy.

Low grade solar thermal on the other hand is an economically viable option. Again, one has the problem of low angles of solar irradiance and short daylight hours in winter, but for much of the year, it is capable of producing sufficient hot water or at any rate contributing significantly to hot water requirements to be a viable provider for those with a south facing aspect.

Where I live in Spain, low grade solar thermal works far better. It is sufficient to adequately heat swimming pools between May and September/perhaps even to mid October, and with the right tank storage can produce almost year round domestic hot water suitable for a small household. Of course, one important difference between Spain and the UK is clear skies. Usually, there is not a cloud in the sky - with probably close to 330 sunny days a year.

The combination of slightly less polution (certainly aroud the Med coastline), slightly higher angle of incidence of sunlight and substantially greater numbers of clear sky days, means that even in winter (when it is rare for there to be more than 3 consecutive cloudy days), solar thermal for domestic hot water is very worthwhile. Systems can be had for less than €1,000 plus fitting. In fact it is possible to make a DIY system (which probably has about 95% of the efficiency of latest glass tube designs) for a few hundred pounds.

The upshot is that the breakeven costs can be achieved within two or three years, whereas solar pv will probably never pay for itself and could make a house difficult to sell. There is much to recommend about low grade solar thermal even for those who live in the UK.

During week-long spells without sun you would be out of hot water soon, unless you lay on very large hot water storage tanks, say 1500 litres, with much thicker insulation than normally used. I notice that my 250 litre boiler has to use the heat pump about six times a day to keep temperature at the right level.

I have been saying for years: if the greens precious "precautionary principle" means that fossil fuel extraction and generation is risky because of possible indirect effects on the climate, surely directly extracting energy from the wind is far more risky? Ask them and they start talking about "insignificant levels", an argument which never seems to apply to other forms of energy. I think part of it is because they think windmills are simple devices which they understand, fossil fuels involve chemistry and engineering at levels which are akin to witchcraft for them.

It is also interesting to look at the evolution of traditional wind and water power; with the development of steam and later IC power, wind and water mills were adapted to use them for backup power when sufficient wind or water wasn't available when it was needed. As the backups became more reliable and efficient, the cost of maintaining the wind or water machinery meant it was uneconomical and in many cases it was decommissioned.

Average electricity production for February was:- coal 19 GW/hr(43%), Nuclear 8.1GW/hr (18%), gas 1.6 GW/hr (27%), wind 2GW/hr (2%). for 7 hours in Feb wind production was less than 0.1GW/hr, another 133 hrs was between 0.1 and 1 GW/hr, 377 hours between 1 and 3 GW/hr and 145 hours between 3 and 5 GW/hr. Only 3.5 hours for the whole of February was wind producing more than 5 GW/hr. What is the point of wasting billions of pounds building something so unreliable and inefficient as wind turbines?